CTBT Opens for Signature at United Nations

The Comprehensive Nuclear-Test-Ban Treaty opened for signature at the United Nations on Sept. 24, 1996. President Clinton signed it the same day as the first signatory. The treaty prohibits any nuclear weapon test explosion or any other nuclear explosion anywhere. It included an unusual ratification trigger requiring all 44 states listed in Annex 2 — those possessing nuclear reactors in 1996 — to ratify before it could enter into force. China signed the same day. The treaty established the CTBTO Preparatory Commission to build the International Monitoring System. As of 2026, 184 states have signed but eight Annex 2 states including the United States and China still haven't ratified, leaving the treaty perpetually short of entry into force.